[sdiy] Reverb picking up power supply hum

[Rainer Buchty]

On Fri, 24 Apr 2009, Cynthia Webster wrote:

> Grounding for Audio jacks comes Only from the center Output pin of 
> your power supply with the + and - fifteen volt output pins on either 
> side.

The following may sound naive, but bear in mind that I'm no analog guy 
at all:

What I don't understand in this respect is why any audio gear doesn't 
just use differential amplifiers at the input. You have crosstalk of 
some other signal on the input lines, well, you don't see it because you 
just take the difference signal of both lines. You catch a hum, again, 
you don't see it, because you take the difference of both lines rather 
than just one referenced to (local) ground.

Wouldn't that be the easiest way of getting rid of the hum problem or am 
I overlooking something fundamental?

Rainer